InBr₃-Catalyzed Synthesis of Highly Functionalized Piperidines and Benzo[a]Pyrano[2,3-c] Phenazines

Abstract

A versatile, operationally simple and highly efficient protocol for the synthesis of highly functionalized piperidines have been developed by the three-component reaction of aromatic aldehydes, aromatic amines and b-ketoesters catalyzed by InBr₃ in ethanol. Also, InBr₃ is demonstrated to be an efficient catalyst for synthesis of benzo[a]pyrano[2,3-c] phenazines. The significant advantages of this protocol are highlighted by excellent yields, short reaction times, avoidance of toxic solvent and broader substrate scope.

Keywords:

• InBr₃
• highly functionalized piperidines
• benzo[a]pyrano[23-c]phenazine
• EtOH